Cannot read property "source" of undefined

There are now other astronauts in space compared to when the teacher made the video, so we are requesting different URLs with the API of Wikipedia to get the astronaut articles.

At this moment (April 2020) I get back 6 astronauts from open-notify.org. Looking at the data I get back from the Wikipedia API, I see 5 of the 6 requests for the astronauts give a 200 response. One fails with a 404 - not found. From the 5 responses I get back from Wikipedia you get an array output like this:

0: {type: "disambiguation", title: "Andrew Morgan", displaytitle: "Andrew Morgan", namespace: {…}, wikibase_item: "Q16263257", …}
1: {type: "standard", title: "Oleg Skripochka", displaytitle: "Oleg Skripochka", namespace: {…}, wikibase_item: "Q927249", …}
2: {type: "no-extract", title: "Chris Cassidy", displaytitle: "Chris Cassidy", namespace: {…}, titles: {…}, …}
3: {type: "standard", title: "Ivan Vagner", displaytitle: "Ivan Vagner", namespace: {…}, wikibase_item: "Q21856852", …}
4: {type: "standard", title: "Jessica Meir", displaytitle: "Jessica Meir", namespace: {…}, wikibase_item: "Q4795114", …}

Only 3 of these responses give back the article of the type 'standard'. Only in that type of response there is a thumbnail.source available. Therefore, only those three get rendered to my page.

I assume you have something similar going on. Hope this helps :-)

There is surely a better way to fix this that can apply to more cases, but right now these names need fixing: Chris Cassidy, Anatoly Ivanishin

btn.addEventListener("click", () => {
  getJSON(astrosUrl, (json) => {
    json.people.map((person) => {
      if (person.name === "Anatoly Ivanishin") {
        person.name = "Anatoli Ivanishin";
      }
      if (person.name === "Chris Cassidy") {
        person.name = "Christopher Cassidy";
      }
      getJSON(wikiUrl + person.name, generateHTML);
    });
  });
});

I fixed it with a dictionary of names.

const imena = {
  'Anatoly': 'Anatoli',
  'Chris': 'Christopher'
};


function getProfile(json) {

  const profiles = json.people.map( (person) => {
    let firstName = person.name.split(' ')[0]; // find the first name

    if (imena[firstName] != undefined) { // if the first name of an astronaut is in the dictionary, replace it 
      person.name = person.name.replace(firstName, imena[firstName]);
    }
    return getJSON(wikiUrl + person.name);
  });
  return Promise.all( profiles );
}